Fish pass assessment by remote control: Towards a
framework for quantifying the hydraulics at fish pass entrances
Thomas Kriechbaumer1, Kim Blackburn1, Andrew Gill1, Toby Breckon2, Nick Everard3, Ros Wright3, Monica Rivas Casado1
1. Target – fish passage at barriers with minimal
delay
Fish pass monitoring studies of the last decades indicate passage
efficiencies below 50% at many fish passes globally, especially for
non-salmonid species. Frequently, this is due to unfavourable nearpass hydraulic conditions, masking the fish pass entrance.
4. Initial results
Identifying ADCP limitations
On rivers, ADCPs are primarily deployed for discharge measurements.
Their use beyond this purpose requires careful considerations of data
quality.
Developing spatial ADCP data referencing approaches beyond
GPS river banks, vegetation
Near
can limit sky view to
navigation satellites. A low
number of satellites “in view”
and unfavourable satellite
geometry (high horizontal
dilution of precision – HDOP)
lead to degraded GPS
position accuracy.
HDOP:
0-1
1-2
2-3
3-4
4-5
Satellites:
4
5
6
7
8
9
10
20m
Fig.5. GPS performance assessment on
the River Avon at Pershore, 12/12/2012
Fig.1. Strong competing flows and potentially weak
attraction at a vertical slot pass on the River Severn,
Shrewsbury, 13/12/2012
Platform track
To overcome GPS limitations, an ADCP positioning system based on
stereo-vision (visual Simultaneous Localisation and Mapping –
SLAM) is developed.
Fig.2. Possible hydraulic features downstream a
weir with a fish pass; strong flows over the barrier
and recirculation zones are masking the pass
entrance..
2. Project aim
This project aims to develop a framework for the rapid quantification
of near-pass hydraulics with Acoustic Doppler Current Profilers
(ADCPs) deployed from radio-controlled boats. The initial steps
focus on alleviating the major limitations of current ADCP
technology.
ADCPs enable the rapid collection of
3.
ADCPs?
vastWhy
amounts
of data on water velocity
and depth, from which other hydraulic
variables can be derived.
Advancing radio-control ADCP deployment
A small-sized radio-control ADCP platform has been developed to facilitate
data collection at fish passes in small rivers. It includes a data-logging
system for multiple-sensor integration and the hardware for autonomous
platform control to facilitate the implementation of sampling strategies.
Water depth
[m)
Increasing ADCP measurement resolution
ADCP-derived 3D velocities are
based on measurements along all
four ADCP beams. This leads to a
decreasing spatial
resolution
with
a)
increasing measurement depth.
Approaches to increase the
resolution are currently tested.
Fig.3. ADCP-measured water velocities and depths
Water velocity
[ms-1]
Distance made good
(m)
Fig.7. Spatial resolution of 3D velocities measured with a
RioGrande 1200kHz ADCP
Fig.4. New platform carrying a RiverSurveyor M9 ADCP on the River Thames at Eynsham, 06/02/2014
www.cranfield.ac.uk/sas
1Cranfield
Fig.6. Capturing stereo-images (left), estimating scenery depth based on stereo-disparity (middle) and tracking of salient
features (right) are major steps in visual SLAM.
University, Department of Environmental Science and Technology, Cranfield, UK, t.kriechbaumer@cranfield.ac.uk,+44 07454 001948
2Durham University, School of Engineering and Computing Sciences, Durham, UK
3Environment Agency, Wallingford and Feering, UK
© Cranfield University 2014